The field of cabinetry includes a number of skills and techniques in the production of various cabinet units. However, basic to nearly every sort of cabinet structure is the joining of the basic four planar members of the cabinet unit. These four planar members are constructed to make a rectangular annular shaped member which includes a first, usually upper horizontal member, a second, usually lower horizontal member, a first vertical wall joining the first and second horizontal members on one side and a second vertical wall joining the first and second horizontal members on the other side. The result is the basic annular, usually rectangular shaped, box open on two, usually a front and a rear side. Other reinforcements are usually added on the rear open side for stabilizing the integrity of the box, while a door, drawers or other openable and closable utility structure will appear at the front side as well as other stabilizing cross members.
Of course other processes are applied to cabinet structures, but the bulk of cabinet units begin with a rectangular box, whether the cabinet may include a lower unit and an upper unit, or an integrated upper and lower unit. Because this basic annular, usually rectangular shaped basic box unit is the basis for steps and structures employed thereafter, it is very important that this be constructed with as much strength and accuracy as possible. Expensive CNC (computer numerical controlled) or line boring machines are used for this purpose and provide for accurate placement of the drilled holes for fasteners and dowels. Dowels insure proper alignment and in the assembly process accurately locate and position the joining surfaces while screws are used to secure the panels one to the other in order to form the complete annular shaped box structure which is the basic building block for what becomes a “cabinet”. In general, the use of dowels is important because of their potential to provide proper alignment and fit when the bores they utilized are properly formed. Other structures which are used for joining panels such as biscuits and loose tenons do not enable the type of accuracy of joining that a properly placed dowel can offer.
In general, in the case of the first and second horizontal members, they are usually located with dowels and engaged with threaded fasteners members which extend parallel with the plane of those members. In the case of the first and second vertical wall members, they are usually located outside the end edges of the first and second horizontal members and usually are engaged with dowels which interfit between blind bores drilled perpendicularly into the vertical members and are also engaged with threaded fasteners which extend perpendicularly into the vertical members and extend through and into the first and second horizontal members. In this way the first and second horizontal members can be strongly supported by the first and second vertical members by the stronger lateral sheer strength of the threaded fasteners and dowels.
The aforementioned arrangement of the basic annular, usually rectangular shaped box open on two sides, may be done under conditions of automated processing with a relative expensive computer numerically controlled (CNC) machinery or line boring machines. The CNC machining process enables computer controlled exact depth formation of the blind bores which will perfectly fit a dowel pin, and the formation of threaded fastener through bores and blind bores which will align perfectly at the time of assembly. Such computer controlled machining solution may be economically justifiable where a large number of uniform cabinets are being manufactured. But the cabinet industry is much more predominantly a custom design and manufacturing business. Cabinets are typically designed and constructed based upon available space and a combination of specific needs.